The present invention relates to a transformer bobbin with hipot-protect structure, and more particularly to a transformer bobbin having portion or portions extended from one or two pin-connection sides to provide increased creepage distance on the extended bobbin between a pin connected thereto and a core of the transformer for preventing a hipot from directly crossing over the core between pins at two sides of the bobbin and thereby complying with relevant safety code.
Transformers are required components in electronic circuits. Since circuit boards used in the existing electronic products are very thin, small and light in volume, transformers used for constructing the circuit boards also require largely reduced size. However, all transformers mainly structurally include a bobbin, multiple pins, a core, and a winding. While transformers of different specifications provide different voltage-change function, they all have to comply with relevant safety codes specifying safe and protective requirements thereof. Among the safety codes, there is one particularly concerning "creepagedistance". The creepage distance may be 1.6 mm, 2.5 mm or other length, depending on grades, such as A or B grade, specified in the code. The purpose of creepage distance is to define a safety distance between two metal components so as to prevent hipot occurred at lightning, for example, from directly crossing over a conductive metal component to another metal component and resulting in damages, such as short circuit, to other components in the same circuit. Such safety distance must exist between the winding and the core, the pins and the second winding, or the pins and core. For the existing transformers of different specifications, there are different isolating means respectively provided to achieve the required safety distances between different components. In the present invention, a hipot-protect structure is provided on the bobbin of a transformer to achieve an increased creepage distance between the pins and the core to comply with relevant safety code.